1. Technical Field
This invention relates to a watertight receptacle in which the electrical contacts of the receptacle are not energized when exposed to human touch and in which the electrical plug withdrawal deenergizes the electrical contacts.
2. Description of the Prior Art
Watertight electrical outlet receptacles have been in use at shoreside and shipboard installations for many years. Essentially, one prime application involves electrically powered refrigerated containers being transported on land with the refrigeration being powered by the transporter. Once at dockside or in place on board ship, the refrigeration unit receives its power from an electrical outlet installation which quite obviously must be watertight due to the wet environment and the associated corrosive problem. Experience has shown that the electrical receptacles, which are typically 220 and 440 volt installations, must not only be protected from the environment but also must not have exposed electrical contacts which can be accidentally or inadvertently contacted by a human.
One approach to the problem has been a design wherein reinsertion of the plug into the receptacle automatically activates the electrical contacts and conversely withdrawal of the plug from the receptacle automatically deactivates the contact. However, in certain applications it has been found that after insertion of the plug, the power must be cycled by manually switching the associated circuit breaker.
In attempting to achieve a design which would overcome these problems it is essential to provide reliability and low cost. These apparently incompatible requirements have limited the degree of success of devices of the prior art.